Method of making nonporous articles



Feb. 17, 1931. FIRTH 1,792,581

METHOD OF MAKING NONPOROUS ARTICLES Filed Aug. 12, 1929 A u" 5;" a

Patented Feb. 17, 1931 UNITED STATES LOUIS GERALD FIRTH, O1 PITTSBURGH,

PATENT OFFICE PENNSYLVANIA, ABGIGNOB TO FIRTH- OF PENNBYLVAN IA METHODOF MAKING NONPOROUS ARTICLES Application fled August 12, 1928. SerialNo. 885,256.

This invention relates to a method of making nonporous articles.

Ingotsof steel or other metals or alloys are now usually cast in moldshaving a substantially square cross-section. The ingot molds aresometimes provided with hot-tops through which the metal is poured intothe mold, the hot-tops being used to keep the metal in liquid condition,thereby tending to decrease the amount of shrinks, pipes, an porosity ofthe cast ingot. Even with the use of hot-tops, however, the ingots aresomewhat porous and for certain purposes it is necessary to scrap alarge proportion of the ingot and use only that portion of the ingotwhich is substantially entirel free from orosity, segregation and shrins. In makmg pistons for pneumatic rock-drills, valve seats and valveswhich are to be subjected to great pressures, or for airplane work, orother similar usa es, it is necessary that the metal be substantiallyfree from defects such as segregation, shrinks, or porous structure.

My invention is particularly adapted where it is necessary that theingot be substantially free from the defects above mentioned. The usualprocess of casting ingots as practiced at the present time is to pour 1nsuch a wa that the last ortion to cool is at the top 0 the ingot an maybe discarded. However, in any given cross section of an ingot at rightangles to its longitudinal axis, the last portion to cool is the extremecenter. It is probable that the central 5% to 15% of this cross sectioncools almost similutaneously, i. e., the solidification is progressivefrom the sides of the mold up to a certain point, at which oint more orless simultaneous freezing ta as place. It is this central 5% to 15%which contains the greater part of the segregated 1mpur1- ties andgases. This central portion also usually cools progressively from thebottom of the ingot to the top and it is customary to discard the upperportion or ipe end which, generall speaking, is the ast portion to cool.l t is impracticable, however, under present ractice to discard thewhole of that centrai axis or core which extends from the bottom to thetop of the ingot and which contains the steel last to cool in eachhorizontal plane.

In my invention, I not only discard the top portion of the ingot,according to common practice, but 1 also sever the ingot lon 'tudinallyand discard that portion in eac horizontal plane which was the last tocool. It is in this respect that my invention difiers radically frompresent da practice. The approximate amount of t is last cooled portionto be removed according to my process is from 10% to 30% of the originalweight of the ingot, this bein taken maml rom the central portion of tiecastmg. en a very high degree of perfect1on 1s required, as much as 50%of the original weight may be removed from the central portion. This canbe regulated by cuttin the ingot nearer or further from its centra axis.

In my reference to horizontal planes and longitudinal axis I refer toingots cast upright according to the usual practice, but my Inventioncan also be ap lied when the ingot is cast with the longitu inal axisslop-' ing or horizontal. In accordance with my invention, the ingot iscast in a mold having recesses formed therein which form flanges on theingot extending outwardly from the body portlon of the ingot. Anyshrinks, pipes, or porous structure which may be present in the ingotare in the central portion thereof, and the flanges are free from suchdefects. The flan es are then separated from the relative y porous bodyportion and are worked by rolling or other shaping methods to form thedesired articles.

In the accompanyng drawings, which illustrate several present preferredembodiments of my invention;

Figure 1 is an elevation of an ingot mold;

Figure 2 is a section on the line IIII of Figure 1, showing the ingot inthe mold;

Figures 3 and 4 are sections similar to Figure 2, but showing ingotshaving four and five flanges, respectively;

Figure 5 is a section similar to Figures 2, 3, and 4, but showinganother modification;

Figure 6 is a horizontal section of one of the flanges formed on theingot, after the flange has been separated from the body portion of theingot; and

Figure 7 is a perspective view of a rockdrill iston.

Re erring more particularly to Figs. 1 and 2 of the drawings, there isshown an ingot mold 2 which is generally triangular in shape. The moldis formed of sections 3, 4, and 5, which are bolted together by bolts 6and nuts 7. The mold is provided with recesses 8 extending radially froma central recess 9. The recesses 8 taper outwardly from the centralportion of the mold, for a purpose hereinafter described.

In casting an in ot in the illustrated mold, the metal is poure in theusual manner, refcrably through a hot-top. The metal ows into therecesses 8 to form an ingot having a central body )ortiou 10 and flanges11 extending therefrom. Each of the flanges 11 has its three outer sidescooled by the mold. The side of the flange 11, which is connected to thecentral portion 10 of the ingot, remains hot for a longer time than theother sides of the flan es which contact with the mold sections. hecooling action of the ingot takes place first on the sides exposed tothe mold sections so that the flanges 11 are formed without shrinks,porous spots, or segregation. The only porous portion of the ingot isthe central ortion 10.

The anges 11 are then separated along the lines 15 from the centralportion of the ingot which was the last portion to cool. Afterseparation the flanges, which are entirely solid, are rolled, for ed, orotherwise shaped into the desired articles.

The ingot shown in Figure 3 is similar to the ingot of Fig. 2, exceptthat in Fig. 3 the ingot has four flanges 110: instead of three. Anordinary mold of substantially square cross-section can be convertedinto a mold embodyin my invention b inserting filler blocks 21 in thecorners of t e mold in order to form a mold having recesses 80: whichform flanges 11a on the in t. \Vhen the mold shown in Fig. 3 is use forcasting the ingot, the flanges 11a are separated along the lines 15afrom the central portion of the ingot.

In Fig. 4 there is shown a mold having five recesses 86, which form aningot having five flanges 11b extending radially therefrom. My inventioncontemplates the formation of an in ct having any number of flangesforme thereon.

In Fig. 5 another form of ingot mold is shown. This mold has recesses 80formed therein, which form the flanges 110 on the ingot. It also hasrecesses 25 provided in the mold which form flanges 26 on the ingot.When a mold of this sha e is employed, the flan es 8c are separated romthe remainder of t e ingot along the lines 150 and only the two flanges110 are worked to form the desired articles. The recesses 25 in the moldand the corresponding flanges 26 formed on the ingot are provided inorder to cause the shrinks and segregations to take place as indicatedat 27, and in order that the flanges 110 will be free from such defects.

The illustrated molds are made in sections which are bolted together inorder to free the molds. If desired, solid molds may be employed insteadof split molds, and any number of recesses may be provided in the moldsto form a corresponding number of flan es on the ingots.

The recesses 8, 8a, 8b, and 80, preferably slope outwardly from thecentral portion of the mold. In Fig. 6 there is illustrated a flange 11formed in the mold illustrated in Fig. 2. As above stated, the flanges11 are substantially free from porosity and segregation. However, thereis a small portion 12 of the flange which is not quite as dense as theremaining portion of the flange. This is due to the fact that the ortion12 is the last to cool. In order to ma e the density of the billetrolled from the flange 11 absolutely uniform, the flanges are casthaving a slight taper outwardly from the central portion of the ingot.The inner portion 30 of the flange accordingly is subjected to greaterwork than the outer portion 31 when the flange is rolled. The greateramount of work to which the portion 30 is subjected ives the rolledbillet substantiall uniform ensity throughout.

After rol ing, forging, or otherwise shaping the flange 11, it isformedinto the desired article. a

A piston 35 for a rock-drill is illustrated in Fig. 7. Pistons madeaccording to my invention are free from porosity, shrinks, and otherdefects and are particularly adapted for the work which they have toperform. If a iston for a rock-drill is slightly porous, it is ikely tocrack under the strain imposed by the terrific impact of the pistonagainst the other parts of the rock-drill.

M invention is especially useful in the PlOdXlOtiOll of alloy steelarticles which are expensive and in which it is desired to reduce to aminimum the portion of the ingot which it is necessary to discardbecause of its orous character.

I desired, the ingot may be cast into molds which are rotated in orderto force the metal from the central portion of the mold into therecesses which form the flanges on the ingot.

I have illustrated and described several preferred forms of theinvention. It is to be understood, however, that the invention may beotherwise embodied within the scope of the following claims.

I claim:

1. The method of makin non-porous metal articles, comprising casting themetal to form an ingot having a body ortion and flanges thereon,separating the anges from the body portion and forming the article fromthe flanges.

2. The method of making non-porous metal articles, comprising casting asolid ingot having a body portion of relatively porous metal and flangesof relatively nonporous metal, separatin the flanges from the bodyportion and orming the article from'the flanges.

3. The method of making non-porous steel pistons for pneumatic hammersand drills, comprising castin a steel ingot having a body portion andanges thereon, separating the flanges from the body portion, and forminthe flanges into pistons.

i. The method of making non-porous metal articles, comprising castingthe metal to form an ingot having a body portion and flanges thereon,longitudinally separating the flanges from the body portion, and formingthe article from the flanges.

5. The method of making non-porous metal articles, comprising castingthe metal to form an ingot havingra body portion and flanges extendingthere om, the flanges and body portion being connected throughout themajor portion thereof, longitudinally separating the flanges from thebody portion, and forming the article from the flanges.

6. The method of making non-porous metal articles, comprising castingthe metal to form an in ot havin a body portion and flanges exten mgthere rom, the flanges and body portion being connected throughoutsubstantially their entire lengths, longitudinally separating theflanges from the body portion, and forming the article from the anges.

In testimony whereof I have hereunto set my hand.

L. GERALD FIRTH.

pistons for pneumatic hammers comprising castin body portion and angesthereon, separating the flanges from the body portion, and forming theflanges into pistons.

the body portion and forming the article from the flanges.

2. The method of making non-porous metal articles, comprising castm asolid ingot having a body portion 0 porous metal and flanges ofrelatively nonporous metal, separatin the body portion and from theflanges.

relatively the flanges from orming the article 3. The method of makingnon-porous steel and drills, a steel ingot having a The method of makingnon-porous metal articles, comprising casting the metal to form an ingothaving a body portion and flanges thereon, longitudinally separating theing the article from the flan es.

anges from the body portion, and form- 5. The method of makm non-porousom, the flanges and 6. The method of making non-porous metal articles,comprising casting the metal to form an in at havin a body portion andflanges exten mg there?! body portion being connected throu houtsubstantially their entire lengths, longitudinally separating theflanges from the body om, the flanges and ortion, and forming thearticle from the anges.

In testimony whereof I have hereunto set my hand.

L. GERALD FIRTH.

CERTIFICATE OF CORRECTION.

Patent No. 1,792,581. Granted February 17, 1931, to

It is hereby certified that the christian name of the patentee in theabove numbered patent was erroneously written and printed as "Louis"whereas said name should have been written and printed Lewis; and thatthe and Letters Patent should be read with this correction therein thatthe same may conform to the record of the case in the Patent Office.

Signed and sealed this 17th day of March, A. D. 1931.

M. J. Moore,

(Seal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

Patent No. 1,792,581. Granted February 17, 193], to

It is hereby certified that the christian name of the patentee in theabove numbered patent was erroneously written and printed as "Louis"whereas said M. J. Moore. (Seal) Acting Commissioner of Patents.

